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LIMIT Clause
Время создания: 30.09.2017 22:03
Раздел: Postgres - syntaxis
Запись: xintrea/mytetra_db_mcold/master/base/1506798190tmza10m0ya/text.html на raw.githubusercontent.com
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The PostgreSQL LIMIT clause is used to limit the data amount returned by the SELECT statement. Syntax The basic syntax of SELECT statement with LIMIT clause is as follows − SELECT column1, column2, columnN
FROM table_name
LIMIT [no of rows]
The following is the syntax of LIMIT clause when it is used along with OFFSET clause − SELECT column1, column2, columnN
FROM table_name
LIMIT [no of rows] OFFSET [row num]
LIMIT and OFFSET allow you to retrieve just a portion of the rows that are generated by the rest of the query. Example Consider the table COMPANY having records as follows − # select * from COMPANY;
id | name | age | address | salary ----+-------+-----+-----------+--------
1 | Paul | 32 | California| 20000 2 | Allen | 25 | Texas | 15000 3 | Teddy | 23 | Norway | 20000 4 | Mark | 25 | Rich-Mond | 65000 5 | David | 27 | Texas | 85000 6 | Kim | 22 | South-Hall| 45000 7 | James | 24 | Houston | 10000 (7 rows) The following is an example, which limits the row in the table according to the number of rows you want to fetch from table − testdb=# SELECT * FROM COMPANY LIMIT 4; This would produce the following result − id | name | age | address | salary
----+-------+-----+-------------+--------
1 | Paul | 32 | California | 20000
2 | Allen | 25 | Texas | 15000
3 | Teddy | 23 | Norway | 20000
4 | Mark | 25 | Rich-Mond | 65000
(4 rows)
However, in certain situation, you may need to pick up a set of records from a particular offset. Here is an example, which picks up three records starting from the third position − testdb=# SELECT * FROM COMPANY LIMIT 3 OFFSET 2; This would produce the following result − id | name | age | address | salary
----+-------+-----+-----------+--------
3 | Teddy | 23 | Norway | 20000
4 | Mark | 25 | Rich-Mond | 65000
5 | David | 27 | Texas | 85000
(3 rows) |
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Так же в этом разделе:
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